Re: [Libguestfs] [PATCH nbdkit 2/2] tar: Rewrite the tar plugin (again), this time in C.

+ +static int +tar_get_ready (void) +{ + FILE *fp; + CLEANUP_FREE char *cmd = NULL; + size_t len = 0; + bool scanned_ok; + char s[256]; + + /* Construct the tar command to examine the tar file. */ + fp = open_memstream (&cmd, &len); + if (fp == NULL) { + nbdkit_error ("open_memstream: %m"); + return -1; + } + fprintf (fp, "LANG=C tar --no-auto-compress -tRvf ");

+ shell_quote (tarfile, fp);

+ fputc (' ', fp); + shell_quote (file, fp); + if (fclose (fp) == EOF) { + nbdkit_error ("memstream failed: %m"); + return -1; + } + + /* Run the command and read the first line of the output. */ + nbdkit_debug ("%s", cmd); + fp = popen (cmd, "r"); + if (fp == NULL) { + nbdkit_error ("tar: %m"); + return -1; + } + scanned_ok = fscanf (fp, "block %" SCNu64 ": %*s %*s %" SCNu64, + &offset, &size) == 2; + /* We have to now read and discard the rest of the output until EOF. */ + while (fread (s, sizeof s, 1, fp) > 0) + ; + if (pclose (fp) != 0) { + nbdkit_error ("tar subcommand failed, " + "check that the file really exists in the tarball"); + return -1; + } + + if (!scanned_ok) { + nbdkit_error ("unexpected output from the tar subcommand"); + return -1; + } + + /* Adjust the offset: Add 1 for the tar header, then multiply by the + * block size. + */ + offset = (offset+1) * 512; + + nbdkit_debug ("tar: offset %" PRIu64 ", size %" PRIu64, offset, size); + + /* Check it looks sensible. XXX We ought to check it doesn't exceed + * the size of the tar file. + */ + if (offset >= INT64_MAX || size >= INT64_MAX) { + nbdkit_error ("internal error: calculated offset and size are wrong"); + return -1; + } + + return 0; +} + +struct handle { + int fd; +}; + +static void * +tar_open (int readonly) +{ + struct handle *h; + + assert (offset > 0); /* Cannot be zero because of tar header. */ + + h = calloc (1, sizeof *h); + if (h == NULL) { + nbdkit_error ("calloc: %m"); + return NULL; + } + h->fd = open (tarfile, (readonly ? O_RDONLY : O_RDWR) | O_CLOEXEC); + if (h->fd == -1) { + nbdkit_error ("%s: %m", tarfile); + free (h); + return NULL; + } + + return h; +} + +#define THREAD_MODEL NBDKIT_THREAD_MODEL_PARALLEL + +/* Get the file size. */ +static int64_t +tar_get_size (void *handle) +{ + return size; +} + +/* Serves the same data over multiple connections. */ +static int +tar_can_multi_conn (void *handle) +{ + return 1; +} + +static int +tar_can_cache (void *handle) +{ + /* Let nbdkit call pread to populate the file system cache. */ + return NBDKIT_CACHE_EMULATE; +} + +/* Read data from the file. */ +static int +tar_pread (void *handle, void *buf, uint32_t count, uint64_t offs)

+{ + struct handle *h = handle; + + offs += offset; + + while (count > 0) { + ssize_t r = pread (h->fd, buf, count, offs); + if (r == -1) { + nbdkit_error ("pread: %m"); + return -1; + } + if (r == 0) { + nbdkit_error ("pread: unexpected end of file"); + return -1; + } + buf += r; + count -= r; + offs += r; + } + + return 0; +} + +/* Write data to the file. */ +static int +tar_pwrite (void *handle, const void *buf, uint32_t count, uint64_t offs) +{ + struct handle *h = handle; + + offs += offset; + + while (count > 0) { + ssize_t r = pwrite (h->fd, buf, count, offs); + if (r == -1) { + nbdkit_error ("pwrite: %m"); + return -1; + } + buf += r; + count -= r; + offs += r; + } + + return 0; +} + +static struct nbdkit_plugin plugin = { + .name = "tar", + .longname = "nbdkit tar plugin", + .version = PACKAGE_VERSION, + .unload = tar_unload, + .config = tar_config, + .config_complete = tar_config_complete, + .config_help = tar_config_help, + .magic_config_key = "tar", + .get_ready = tar_get_ready, + .open = tar_open, + .get_size = tar_get_size, + .can_multi_conn = tar_can_multi_conn, + .can_cache = tar_can_cache, + .pread = tar_pread, + .pwrite = tar_pwrite, + .errno_is_preserved = 1, +}; + +NBDKIT_REGISTER_PLUGIN(plugin) diff --git a/tests/test-dump-plugin.sh b/tests/test-dump-plugin.sh index 0b4c1ce1..6eb25a65 100755 --- a/tests/test-dump-plugin.sh +++ b/tests/test-dump-plugin.sh @@ -46,7 +46,7 @@ do_test () python-valgrind | ruby-valgrind | tcl-valgrind) echo "$0: skipping $1$vg because this language doesn't support valgrind" ;; - example4* | tar*) + example4*) # These tests are written in Perl so we have to check that # the Perl plugin was compiled. if nbdkit perl --version; then run_test $1; fi diff --git a/tests/test-help-plugin.sh b/tests/test-help-plugin.sh index 7dc26ece..f0dfa7df 100755 --- a/tests/test-help-plugin.sh +++ b/tests/test-help-plugin.sh @@ -46,7 +46,7 @@ do_test () python-valgrind | ruby-valgrind | tcl-valgrind) echo "$0: skipping $1$vg because this language doesn't support valgrind" ;; - example4* | tar*) + example4*) # These tests are written in Perl so we have to check that # the Perl plugin was compiled. if nbdkit perl --version; then run_test $1; fi diff --git a/tests/test-tar-info.sh b/tests/test-tar-info.sh new file mode 100755 index 00000000..efaa8ec8 --- /dev/null +++ b/tests/test-tar-info.sh @@ -0,0 +1,67 @@ +#!/usr/bin/env bash +# nbdkit +# Copyright (C) 2017-2020 Red Hat Inc. +# +# Redistribution and use in source and binary forms, with or without +# modification, are permitted provided that the following conditions are +# met: +# +# * Redistributions of source code must retain the above copyright +# notice, this list of conditions and the following disclaimer. +# +# * Redistributions in binary form must reproduce the above copyright +# notice, this list of conditions and the following disclaimer in the +# documentation and/or other materials provided with the distribution. +# +# * Neither the name of Red Hat nor the names of its contributors may be +# used to endorse or promote products derived from this software without +# specific prior written permission. +# +# THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND +# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, +# THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A +# PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR +# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF +# USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND +# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, +# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT +# OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +# SUCH DAMAGE. + +# Test that qemu-img info works on a qcow2 file in a tar file. + +source ./functions.sh +set -e +set -x + +requires test -f disk +requires guestfish --version +requires tar --version +requires qemu-img --version +requires qemu-img info --output=json /dev/null +requires jq --version +requires stat --version + +disk=tar-info-disk.qcow2 +out=tar-info.out +tar=tar-info.tar +files="$disk $out $tar" +rm -f $files +cleanup_fn rm -f $files + +# Create a tar file containing a known qcow2 file. +qemu-img convert -f raw disk -O qcow2 $disk +tar cf $tar $disk + +# Run nbdkit. +nbdkit -U - tar $tar file=$disk --run 'qemu-img info --output=json $nbd' > $out +cat $out + +# Check various fields in the input. +# Virtual size must be the same as the size of the original raw disk. +test "$( jq -r -c '.["virtual-size"]' $out )" -eq "$( stat -c %s disk )" + +# Format must be qcow2. +test "$( jq -r -c '.["format"]' $out )" = "qcow2" diff --git a/tests/test-tar.sh b/tests/test-tar.sh index c6d726c4..3164b826 100755 --- a/tests/test-tar.sh +++ b/tests/test-tar.sh @@ -38,23 +38,27 @@ requires test -f disk requires guestfish --version requires tar --version -# The tar plugin requires some Perl modules, this checks if they are -# installed. -requires perl -MCwd -e 1 -requires perl -MIO::File -e 1 - sock=`mktemp -u` files="tar.pid tar.tar $sock" rm -f $files cleanup_fn rm -f $files -# Create a tar file containing the disk image. -tar cf tar.tar disk +# Create a tar file containing the disk image plus some other random +# files that hopefully will be ignored. +tar cf tar.tar test-tar.sh Makefile disk Makefile.am +tar tvvf tar.tar # Run nbdkit. start_nbdkit -P tar.pid -U $sock tar tar=tar.tar file=disk -# Now see if we can open the disk from the tar file. -guestfish -x --ro --format=raw -a "nbd://?socket=$sock" -m /dev/sda1 <<EOF +# Now see if we can open, read and write the disk from the tar file. +guestfish -x --format=raw -a "nbd://?socket=$sock" -m /dev/sda1 <<EOF cat /hello.txt + + # Write a new file. + write /test.txt "hello" + cat /test.txt EOF + +# Check that the tar file isn't corrupt. +tar tvvf tar.tar diff --git a/tests/test-version-plugin.sh b/tests/test-version-plugin.sh index 7d2ab072..c397afc2 100755 --- a/tests/test-version-plugin.sh +++ b/tests/test-version-plugin.sh @@ -46,7 +46,7 @@ do_test () python-valgrind | ruby-valgrind | tcl-valgrind) echo "$0: skipping $1$vg because this language doesn't support valgrind" ;; - example4* | tar*) + example4*) # These tests are written in Perl so we have to check that # the Perl plugin was compiled. if nbdkit perl --version; then run_test $1; fi diff --git a/wrapper.c b/wrapper.c index b1e2ce2f..c27afae0 100644 --- a/wrapper.c +++ b/wrapper.c @@ -85,7 +85,7 @@ static size_t len; static bool is_perl_plugin (const char *name) { - return strcmp (name, "example4") == 0 || strcmp (name, "tar") == 0; + return strcmp (name, "example4") == 0; } static void diff --git a/.gitignore b/.gitignore index f02d19dc..48a5302e 100644 --- a/.gitignore +++ b/.gitignore @@ -79,7 +79,6 @@ plugins/*/*.3 /plugins/ocaml/nbdkit-ocamlexample-plugin.so /plugins/rust/Cargo.lock /plugins/rust/target -/plugins/tar/nbdkit-tar-plugin /plugins/tmpdisk/default-command.c /podwrapper.pl /server/local/nbdkit.pc diff --git a/README b/README index 4f584828..7733761e 100644 --- a/README +++ b/README @@ -124,13 +124,13 @@ For the bittorrent plugin: - libtorrent-rasterbar (https://www.libtorrent.org) -For the Perl, example4 and tar plugins: +For the Perl and example4 plugins: - perl interpreter - perl development libraries - - perl modules ExtUtils::Embed, IO::File and Cwd + - perl modules ExtUtils::Embed For the Python plugin: -- 2.25.0